Apparatus for attaching a dispenser cathode to a support

ABSTRACT

Method and apparatus for attaching a dispenser cathode to a support structure is disclosed. The dispenser cathode body includes a peripherally directed groove into which the end of a tubular support structure is crimped. A retaining wire is forced into the groove containing the crimped end of the support to produce an interference fit between the retaining wire, support structure and the cathode body.

United States Patent Duchmann et al.

[ 51 Jan. 18, 1972 [54] APPARATUS FOR ATTACHING A DISPENSER CATHODE TO ASUPPORT [72] Inventors: Charles A. Duchmann, San Mateo; George V. Miram,Daly City, both of Calif.

[73] Assignee: Varian Associates, Palo Alto, Calif.

[22] Filed: July 22, 1969 211 Appl. No.1 343,570

52 us. Cl. ..313/34@ R, 313/337, 29/2 5l19,

29/229 [51] Int. Cl. ..1'101j 1/14 [58] Field of Search ..29/25. 1 7,229, 25.11, 25.13, 29/25.14, 25.15, 25.19; 313/238, 341, 346 R, 337

[56] References Cited UNITED STATES PATENTS 3,100,273 8/1963 Huse..313/337 3,273,003 9/1966 Dietrich ..313/337 3,440,475 4/1969 Schiller.

1,958,638 5/1934 Olen.....

2,l80,27l 11/1939 Arras....

2,760,258 8/1956 Rieger 3,088,192 5/1963 Turner ..29/501 PrimaryExaminer-John F. Campbell Assistant Examiner-Donald P. RooneyAttomey-Stanley Z. Cole and Gerald L. Moore [57] ABSTRACT Method andapparatus for attaching a dispenser cathode to a support structure isdisclosed. The dispenser cathode body includes a peripherally directedgroove into which the end of a tubular support structure is crimped. Aretaining wire is forced into the groove containing the crimped end ofthe support to produce an interference fit between the retaining wire,support structure and the cathode body.

4 Claims, 1 Drawing Figure PATENTED JAN 1' a ma INVENTORS CHARLES A.DUCHMANN GEORGE V. MIRAM ATTORNEY APPARATUS FOR ATTACIIING A DISPENSERCATIIODE TO A SUPPORT DESCRIPTION OF THE PRIOR ART Heretofore, dispensercathode bodies have been attached to tubular support structures by meansof crimping the end of the tubular support against the outer peripheryof the cathode body or against a retaining ring carried in a groovearound the periphery of the cathode body. The problem with merelycrimping the end of the cathode tubular support structure against thecathode body is that repeated thermal cycling of the cathode and itssupport structure, as encountered in use, produces a mechanical workingof the crimped end of the tube relative to the cathode body whichresults in producing a loose connection between the cathode body and thesupport structure. This loose connection impedes the flow of cathodecurrent and causes the beam to have substantial noise superimposedthereon in use. In the case where the cathode support structure iswelded, as by spot welding, to a ring carried within a groove in thecathode body, the mechanical working causes the welded points to breakloose causing the beam current to be diverted to the remaining weldswhich overtaxes these welds and causes them to burn out. As a result,the tube becomes noisy and leads to cathode failure.

SUMMARY OF THE PRESENT INVENTION The principal object of the presentinvention is the provision of an improved method andapparatus forattaching a dispenser cathode to a cathode support structure.

One feature of the present invention is the provision of a groove aroundthe periphery of a dispenser cathode body into which a portion of thetubular cathode support structure is crimped and including the provisionof a retaining wire wedged into the groove to produce a tightinterference fit between the wire, the support structure and the cathodebody.

Another feature of the present invention is the same as the precedingfeature wherein the retaining wire is connected together at its ends toform a retaining ring.

Other features and advantages of the present invention will becomeapparent upon a perusal of the following specification taken inconnection with the accompanying drawing which is a longitudinal view,partly in section, depicting a dispenser cathode attached to its supportstructure and incorporating features of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawing,there is shown a dispenser cathode I attached to its support structure 2and incorporating features of the present invention. More particularly,the cathode emitter 1 includes a cylindrical cathode emitter body 3, asof impregnated tungsten or thoriated tungsten. In a preferred embodimentthe cathode emitter body 3 is a porous tungsten body with the boresbeing impregnated with cathode emitter material such as barium oxide,barium strontium aluminate or barium strontium tungstate. The cathodeemitter body 3 includes a spherically concave cathode emitting surfacefrom which the electrons are emitted to produce a beam of electrons foruse in an electron beam tube.

A groove 4 is provided around the periphery'of the cathode body 3.Cathode emitter body 3 is carried from the end of a tubular cathodesupport member 2, as of 0.003 to 0.005 inch thick tantalum tubing. Thesupport end of the tubing 2 is crimped around the marginal lip 5 of thecathode body 3 with the end portion of the tubular support 2 beingcrimped into the groove 4.

A retaining wire 6, as of 0.030-inch diameter tantalum, is wedged intothe groove 4 to produce a tight interference fit between the retainingwire 6, the end of the support tube 2, and the cathode body 3. The twoends of the retaining wire 6 are spotwelded together at 7 to fonn aretaining ring structure tightly wedged into the groove 4.

The heating structure, not shown, is positioned inside the tubular suport structure 2 at the back side of the emitter body 3 for eating theemitter body 3 to operating temperature, as of 1,100" C.

In a typical example, the emitter body 3 is made of porous tungsten withthe pores infiltrated with cathode emitter material to fonn a dispensercathode. The cathode has a diameter of l.l65 inches and a minimumthickness, on its axis of revolution, of 0.125 inch. The cathode drawsbetween 5 and 10 amps of cathode beam current, in use.

The advantage of the cathode and its method of attachment, as shown inthe drawing, is that electrical connection between the tubular supportstructure 2 and the cathode body 2 is made through the tight mechanicalinterference fit which is maintained due to the provision of theretaining ring 6. These mechanical connections do not work loose withcontinued thermal cycling of the cathode such that the operating lifeand the noise figure for the beam are substantially improved over priorart methods of attaching the cathode bodies to the support structures.

Since many changes could be made in the above construction and manyapparently widely different embodiments of this invention could be madewithout departing from the scope thereof, it is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In a dispenser cathode emitter structure, means forming a dispensercathode emitter body, means forming a tubular support structure forsupporting said cathode emitter body, means for attaching said supportstructure to said cathode emitter body, the improvement wherein, saidcathode emitter body includes a groove extending around the periphery ofsaid emitter body, said attaching means including a portion of saidtubular support structure extending radially into said groove, and aretaining wire structure in said groove, said retaining wire structurebeing dimensioned to provide, together with said portion of said supportstructure, an interference fit in said groove for fixedly attaching saidcathode emitter body to said support structure.

2. The apparatus of claim 1 wherein an end portion of said tubularsupport structure extends into said groove.

3. The apparatus of claim 2 wherein said dispenser cathode I bodyincludes a porous tungsten body having the pores thereof infiltratedwith an emitter material.

4. The apparatus of claim 2 wherein said retaining wire is an unbrokenretaining ring.

1. In a dispenser cathode emitter structure, means forming a dispensercathode emitter body, means forming a tubular support structure forsupporting said cathode emitter body, means for attaching said supportstructure to said cathode emitter body, the improvement wherein, saidcathode emitter body includes a groove extending around the periphery ofsaid emitter body, said attaching means including a portion of saidtubular support structure extending radially into said groove, and aretaining wire structure in said groove, said retaining wire structurebeing dimensioned to provide, together with said portion of said supportstructure, an interference fit in said groove for fixedly attaching saidcathode emitter body to said support structure.
 2. The apparatus ofclaim 1 wherein an end portion of said tubular support structure extendsinto said groove.
 3. The apparatus of claim 2 wherein said dispensercathode body includes a porous tungsten body having the pores thereofinfiltrated with an emitter material.
 4. The apparatus of claim 2wherein said retaining wire is an unbroken retaining ring.